One feature that faders have is clear visual and haptic feedback - a thing that is not as clear with knobs. For rotary controls not only are the markings smaller if they exist at all but you have to deal with angles instead of distances, for which we know from studies of pie charts for example, our brains are not well equipped for. Then there is the problem that for haptics you need a marking on the circumfence which you can't see in every position, so you need another marker on top - I,ve rarely seen this design. I assume a blind person could use a fader easily but not necessarily a knob.

Where all of this becomes relevant is when we consider digital controllers. If we accept knobs without any visual and physical markings at all we gain an important feature - we can save and recall pot positions. Visual feedback can be regained with a display or a ring of LEDs around the knob or both. With a physical fader all of this is hard to achieve. You need motorized faders, which exist, but are expensive and have a bunch of disadvantages.